1. Field of the Invention
This invention pertains to digital processing machines for processing two-dimensional images. More particularly, this machine pertains to the detection of corners in video images where the images are transformed in two dimensions by means of the Haar transform and are represented in the transform domain by two-dimensional arrays of Haar transform coefficients.
2. Description of the Prior Art
Various systems have been developed to recognize specific images, see e.g. "Pattern Identifying Systems", U.S. Pat. No. 3,869,697; "Character Recognition Apparatus", U.S. Pat. No. 3,846,752; and "Pattern Recognition Apparatus", U.S. Pat. No. 3,597,731. These systems operate on the two-dimensional video picture to recognize a specified image such as a letter in the alphabet.
Other machines have been developed for detecting lines and edges utilizing the Hadamard transform, see e.g. "Pattern Recognition Machine for Analyzing Line Orientation ", U.S. Pat. No. 4,005,385. A system has also been developed for recognizing corners when the outline of the object is defined as a series of points, see "Automatic Corner Recognition System", U.S. Pat. No. 3,576,980. The latter system operates in the image domain and requires as an input the location of a series of points which lie on the boundary of the image.